BART officials say a bundle of electrical cables that send information between rail cars is likely responsible for Friday morning's delays into San Francisco.

The cables are responsible for sending signals from the operator's cab to each of the cars in a train. It appears the cables failed on the fifth car, causing the following five cars to lock up and shut down as it was approaching the West Oakland station, according to a BART spokesman.

Engineers are still investigating the exact source of the glitch and probably won't know for a few days.

The disruption began at about 7:20 a.m. and service resumed into San Francisco at around 8:40 a.m. after the disabled BART train was cleared from tracks at the West Oakland station.